Effects of microstructure on hydrogen-induced cracking in aluminum alloys

Studying hydrogen–microstructure interactions is difficult in Al alloys because H charging is usually coupled with some dissolution of the surface in aqueous media. H uptake therefore depends on the microstructure. An intermediate electrodeposited Ni layer is used to solve this problem. It is shown that an enhanced intergranular precipitation, obtained by holding the samples at 400 °C before the hardening heat treatment increases the resistance of an AlZnMg alloy by changing the fracture mechanism from intergranular brittle to intergranular ductile.